Merge pull request #17 from seanchen1991/master

Add 2020-10-12 Meeting Notes

Author: yaahc

meetings/2020-10-12.md

@@ -0,0 +1,142 @@
+# PEH Meeting Agenda - 2020-10-12
+
+###### tags: `Error Handling` `Minutes`
+
+- [2020-09-28 Meeting Minutes](https://hackmd.io/th5k9_pBRBGmpgnFWJzUHw?both)
+
+## Action Items
+
+- Implement trait based proof of concept for `Backtrace` in `core` (Jane Lusby)
+- Setup `The Rust Error Book` (must-compute, Charles Ellis O'Riley Jr, and Jakub Duchniewicz)
+- Draft a [blog post](https://hackmd.io/GMLcORX_R7W4de0ZryDIxg?view) detailing the long-term vision of what this group thinks Rust error handling should look like (Sean Chen)
+- Status Updates on Tracked issues (What's the current status, what are the next steps, what are the blockers, is it actively being worked on)
+    - [Generic Member Access](https://github.com/rust-lang/rfcs/pull/2895) (Jane Lusby)
+    - [Fix the error trait / Stabilizing Backtrace](https://github.com/rust-lang/rust/issues/53487) (Jane Lusby)
+    - [stabilizing error source iterators](https://github.com/rust-lang/rust/issues/58520) (Oliver)
+    - [Box error alias](https://github.com/rust-lang/rfcs/pull/2820) (unassigned)
+    - [stabilizing Error::type_id](https://github.com/rust-lang/rust/issues/60784) (Jakub Duchniewicz)
+    - [PanicInfo::message](https://github.com/rust-lang/rust/issues/66745) (DPC)
+    - [nicer assert messages](https://github.com/rust-lang/rust/issues/44838) (Charles Ellis O'Riley Jr.)
+ - Moving forward with adding an iterator API to `backtrace` (Sean Chen)
+
+## Agenda Items
+
+- Review action items from last meeting
+- Review open issues on project group repository
+- Anything to buble up to the Libs meeting?
+
+# Meeting Minutes
+
+## Participants
+
+People in attendance:
+- Jane Lusby
+- Sean Chen
+- Ashley Mannix
+- Kyle Strand
+- Lance Zhang
+- Jeremiah Senkpiel
+- Jakub Duchniewicz
+- DPC
+- oliver
+- Charles Ellis O'Riley Jr.
+- must-compute
+- Jubilee Young
+
+## Backtrace in core
+
+- So far the implementation is moving forward fine, but there are questions around the hooks
+- Not clear how to set them up with a default in `no_std` so users don't _need_ to write one like `#[panic_handler]`
+- Current work in progress [here](https://github.com/rust-lang/rust/pull/77384)
+- There's enough sketched out that it shouldn't be a blocker for stabilizing `backtrace` anymore
+
+## The Rust Error Book
+
+- We now have a folder in the `project-error-handling` repository for content
+
+## Log-term project group vision and goals
+
+- Draft here: https://hackmd.io/GMLcORX_R7W4de0ZryDIxg?view
+
+## Generic member access RFC
+
+- There's an updated API in `object-provider` that the RFC would like to use
+- Once the content is updated it needs some Libs input
+- There could be some tie in with `tide`'s `Response` type?
+
+## Fix the `Error` trait / Stabilizing `backtrace`
+
+- Covered in the earlier discussion on _Backtrace in core_
+- There could be some documentation work to do on `backtrace`
+
+## Stabilizing `Error` source iterators
+
+- stabilizing error source iterators
+  - trait objects vs. provided methods
+  - [stabilization report 2020-09-14](https://github.com/rust-lang/rust/issues/58520#issuecomment-691982191)
+    - unergonomic use-cases ---> difficulties stabilizing
+    - bugs
+  - blocked on [#53487](https://github.com/rust-lang/rust/issues/53487)
+- [#75180](https://github.com/rust-lang/rust/pull/75180) might feed into this too
+- related crate [`error-chain`](https://crates.io/crates/error-chain)
+
+## Stabilizing `Error::type_id`
+
+- Several possible approaches, but all are waiting for other stabilizations/RFCs
+    - #[marker] trait stabilization: https://github.com/rust-lang/rust/issues/29864
+    - negative trait impls
+    - dynamic vtable type_id (like C++ typeid keyword) https://github.com/rust-lang/rfcs/pull/2580
+    - final keyword -> no overriding of trait any more
+    - new trait TypeInfo https://github.com/rust-lang/rfcs/pull/2738
+- Not clear it's something we want to stabilize
+- Looks like a rabbit hole we don't want to go down right now
+
+## `PanicInfo::message`
+
+- No progress made here
+
+## Nicer Assert Messages
+
+- [RFC](https://github.com/rust-lang/rfcs/pull/2011) has been approved, with no implementation started yet 
+- Does this need to be implemented using the compiler's built-in proc macros, or can it be done as an external crate using `pro-macros` and `syn`?
+    - Need external thoughts/mentorship on this question
+
+## Iterating over `Backtrace` frames
+
+- Just starting out, so there hasn't been much discussion yet
+- The `backtrace` crate has a `frames()` fn that already exposes its individual frames
+- We could propose basically the same thing for `std`'s `Backtrace` type
+
+# Outcomes
+
+## Backtrace in core
+
+- @KodrAus to ping https://github.com/rust-lang/rust/pull/72981 and raise at Libs meeting RE `backtrace` stabilization
+
+## Long-term project group vision and goals blog post
+
+- @Jane Lusby @Jakub Duchniewicz @KodrAus to review draft content
+
+## Generic member access RFC
+
+- @Jane Lusby to incorporate changes from `object-provider`
+- @KodrAus to review RFC and ping Libs
+
+## Stabilizing `Error` source iterators
+
+- Looks like many parts of this are stuck on fixing the `Error` trait, so our efforts should be focused here to push this forward
+
+## Stabilizing `Error::type_id`
+
+- Putting this one on the back burner
+
+## Nicer Assert Messages
+
+- Look into whether we can implement an external POC for this ourselves
+- Need external advice/mentorship (possibly from t-libs-impl) before we can get started on it
+
+## Iterator API on Backtrace
+
+- @Sean Chen to look more into this initiative
+- Export an identical `fn frames(&self) -> &[BacktraceFrame]` to `std`
+- Add it as an unstable API to `Backtrace` without an RFC to start with (just an FCP on the implementation itself)